Document Type

Thesis - Open Access

Award Date

2017

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Keith Underwood

Keywords

beef, chromium, feedlot steers, growth, insulin signaling, meat quality

Abstract

Chromium supplementation (Cr) can increase efficiency of growth in livestock by amplifying insulin signaling. Previous research showed Cr increases nutrient utilization and changes in muscle growth and fat deposition. Therefore, the objective of this research was to determine how Cr affects carcass traits, meat quality, and the insulin pathway in feedlot steers. Calf-fed steers were allotted to 0 ppb (CON) or 400 ppb Cr propionate (Cr400) for 210d in experiment 1. Two longissimus muscle (LM) biopsies were collected to examine protein abundance and gene expression after adaptation to a terminal implant and after adaption to ractopamine hydrochloride (RAC). A follow up study, Experiment 2, was conducted with yearling steers supplemented 0 ppb (CON) or 300 ppb Cr propionate (Cr300) for 138d. Cattle were transported to a commercial packing plant for slaughter. Carcass data was collected as well as strip loins for shear force and proximate analysis in both experiments. Carcass composition was estimated using 9-10-11 rib dissections with subsequent proximate analysis. Biopsies were used to analyze peroxisome proliferator activated receptor γ (PPARγ), protein kinase B (Akt), phospho- Akt, and ribosomal protein S6 kinase 1 (p70S6K) abundance and glucose transporters (GLUT) 4 and 1 gene expression. Experiment 1 showed an increase in dressing percentage (DP), KPH, and shear force, but a decrease in marbling for Cr400 steers. Final BW, HCW, 12th rib backfat (BF), LMA, yield grade (YG), or carcass composition were not different between treatments. Also, there was no difference in abundance of Akt, phospho-Akt, or p70S6K after the terminal implant, but PPARγ tended to be higher for CON. No differences were observed in protein abundance after RAC supplementation. Expression of GLUT4 and GLUT1 was not different after either biopsy. In experiment 2, there was no difference in final BW, HCW, BF, LMA, YG, DP, marbling score, chemical fat, or shear force. However, percent KPH tended to increase for CON. Variation between studies may be attributed to differences in duration of Cr and the animal model used. In conclusion, earlier and longer Cr supplementation can positively increase DP, but may have negative impacts on beef quality with calf-fed steers.

Library of Congress Subject Headings

Beef cattle -- Feeding and feeds.
Beef cattle -- Carcasses.
Dietary supplements -- Physiological effect.
Chromium.
Beef -- Quality.
Insulin resistance.

Description

Includes bibliographical references (pages 57-75)

Format

application/pdf

Number of Pages

89

Publisher

South Dakota State University

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Included in

Meat Science Commons

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Rights Statement

In Copyright